Transition between transient and steady-state wear in the sliding of poly(phenylene sulfide) against a tool steel counterface

Polyphenylene sulfide (PPS) powders in a grit size of 200 mesh were made into slab specimens in a size of 35 mm × 30 mm × 6 mm by compression molding. The friction and wear behaviors of PPS sliding against a tool steel counterface was studied in a pin-on-disk configuration, with changes in the test parameters, such as load, sliding speed, and counterface roughness. The morphologies of some typical transfer films were observed by optical microscope. The emphasis of this research was placed on the factors that affect the transition between transient and steady wear states. It was found that the transient friction and wear of PPS were significantly affected by initial counterface roughness, sliding speed, and applied load. The wear rate in the transient state increased with the increase in initial counterface roughness, and there was an optimal counterface roughness of 0.06 μm Ra for the minimum steady-state wear rate. A higher applied load led to a higher transient state wear, but did not necessarily lead to a higher steady-state wear unless the applied load was very high. Sliding speed had the greatest influence on transient friction and wear of PPS, particularly at high sliding speeds because of thermal effects. A very low sliding speed did not help in the development of transfer film and resulted in a high wear rate. At the medium sliding speed of 1.0 m s^-1, wear rate was the lowest because of the favorable condition for a uniform transfer film to develop during the transient state.